Isolated, well-defined organovanadium(<scp>iii</scp>) on silica: single-site catalyst for hydrogenation of alkenes and alkynes

Sohn, Hyuntae; Camacho-Bunquin, Jeffrey; Langeslay, Ryan R.; Leon, Patricia A. Ignacio-de; Niklas, Jens; Poluektov, Oleg G.; Liu, Cong; Connell, Justin G.; Yang, Dali; Kropf, Jeremy; Kim, H.; Stair, Peter C.; Ferrandon, Magali; Delferro, Massimiliano

doi:10.1039/c7cc01876b

Cited by 31 publications

(38 citation statements)

References 35 publications

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“…Recently, a similar vanadium complex (V III (Mes) 3 ·THF) has been grafted onto silica and investigated in alkene and alkyne hydrogenations. 26 This bipodal vanadium complex was catalytically active in 1-octene hydrogenation at 70 °C and diphenyl acetylene at 100 °C. The mechanism of these reactions was proposed to be either oxidative addition/reductive elimination or heterolytic activation.…”

Section: Resultsmentioning

confidence: 97%

Parahydrogen-Induced Polarization Study of the Silica-Supported Vanadium Oxo Organometallic Catalyst

et al. 2018

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Parahydrogen can be used in catalytic hydrogenations to achieve substantial enhancement of NMR signals of the reaction products and in some cases of the reaction reagents as well. The corresponding nuclear spin hyperpolarization technique, known as parahydrogen-induced polarization (PHIP), has been applied to boost the sensitivity of NMR spectroscopy and magnetic resonance imaging by several orders of magnitude. The catalyst properties are of paramount importance for PHIP because the addition of parahydrogen to a substrate must be pairwise. This requirement significantly narrows down the range of the applicable catalysts. Herein, we study an efficient silica-supported vanadium oxo organometallic complex (VCAT) in hydrogenation and dehydrogenation reactions in terms of efficient PHIP production. This is the first example of group 5 catalyst used to produce PHIP. Hydrogenations of propene and propyne with parahydrogen over VCAT demonstrated production of hyperpolarized propane and propene, respectively. The achieved NMR signal enhancements were 200–300-fold in the case of propane and 1300-fold in the case of propene. Propane dehydrogenation in the presence of parahydrogen produced no hyperpolarized propane, but instead the hyperpolarized side-product 1-butene was detected. Test experiments of other group 5 (Ta) and group 4 (Zr) catalysts showed a much lower efficiency in PHIP as compared to that of VCAT. The results prove the general conclusion that vanadium-based catalysts and other group 4 and group 5 catalysts can be used to produce PHIP. The hydrogenation/dehydrogenation processes, however, are accompanied by side reactions leading, for example, to C4, C2, and C1 side products. Some of the side products like 1-butene and 2-butene were shown to appear hyperpolarized, demonstrating that the reaction mechanism includes pairwise parahydrogen addition in these cases as well.

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Section: Resultsmentioning

confidence: 97%

Parahydrogen-Induced Polarization Study of the Silica-Supported Vanadium Oxo Organometallic Catalyst

et al. 2018

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“…[82][83][84][85][86][87][88][89][90][91] To gain insight into the active structures for the vanadium catalysed dehydrogenation of propane, silica-supported V III and V V single sites have thus been prepared via SOMC (Scheme 6) using the well-defined V III and V V molecular precursors V III (Mes) 3 (THF) and V V (O)(Mes) 3 . 83,89,92 3). Pre-treatment of (ROSi)V III Mes 2 (THF) under H 2 allows the total suppression of this induction period.…”

Section: St Row Transition Metal Single-site Pdh Catalystsmentioning

confidence: 99%

Heterogeneous alkane dehydrogenation catalysts investigated via a surface organometallic chemistry approach

Docherty¹,

Rochlitz²,

Payard³

et al. 2021

Chem. Soc. Rev.

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“…In the experimental study, 21 the kinetic studies yielded saturation kinetics for styrene but near-first order under standard conditions, close to first order for H2, and first order in V. Using THF as an inhibitor was consistent with reversible dissociation at higher concentrations of THF, but deviation to more significant inhibition at lower levels of THF which could be consistent with poisoning the minority of THF deficient sites. NMR experiments during deuteration shows that the signal of protons on the α-carbon of the styrene diminished more rapidly than the signals associated with the proton at the β-carbon or those associated with the aromatic ring, suggesting that at least some of deuterium was incorporated into the starting styrene by reversible hydride insertion.…”

Section: Correlation With Experimental Mechanistic Studymentioning

confidence: 66%

Computational Investigation of the Role of Active Site Heterogeneity for a Supported Organovanadium(III) Hydrogenation Catalyst

Patel

Wells²,

Kaphan³

et al. 2021

Preprint

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<div> <div> <p></p><p><a>A crucial consideration for supported heterogeneous catalysts is the non-uniformity of the active sites, particularly for Supported Organometallic Catalysts (SOMCs). Standard spectroscopic techniques, such as X-ray absorption spectroscopy (XAS), reflect the nature of the most populated sites, which are often intrinsically structurally distinct from the most catalytically active sites. With computational models, often only a few representative structures are used to depict catalytic active sites on a surface, even though there are numerous observable factors of surface heterogeneity that contribute to the kinetically favorable active species. A previously reported study on the mechanism of a surface organovanadium(III) catalyst [(SiO)V<sup>III</sup>(Mes)(THF)] for styrene hydrogenation yielded two possible mechanisms: heterolytic cleavage and redox cycling. These two mechanistic scenarios are challenging to differentiate experimentally based on the kinetic readouts of the catalyst are identical. To showcase the importance of modeling surface heterogeneity and its effect on catalytic activity, density functional theory (DFT) computational models of a series of potential active sites of [(SiO)V<sup>III</sup>(Mes)(THF)] for the reaction pathways are applied in combination with kinetic Monte Carlo (kMC) simulations. Computed results were t then compared to the previously reported experimental kinetic study</a><a>.: 1) DFT free energy reaction pathways indicated the likely active site and pathway for styrene hydrogenation; a heterolytic cleavage pathway requiring a bare tripodal vanadium site. 2) From the kMC simulations, a mixture of the different bond lengths from the support oxygen to the metal center was required to qualitatively describe the experimentally observed kinetic aspects of a supported organovanadium(III) catalyst for olefin hydrogenation. </a>This work underscores the importance of modeling surface heterogeneity in computational catalysis.</p><p></p></div></div>

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Isolated, well-defined organovanadium(iii) on silica: single-site catalyst for hydrogenation of alkenes and alkynes

Cited by 31 publications

References 35 publications

Parahydrogen-Induced Polarization Study of the Silica-Supported Vanadium Oxo Organometallic Catalyst

Parahydrogen-Induced Polarization Study of the Silica-Supported Vanadium Oxo Organometallic Catalyst

Heterogeneous alkane dehydrogenation catalysts investigated via a surface organometallic chemistry approach

Computational Investigation of the Role of Active Site Heterogeneity for a Supported Organovanadium(III) Hydrogenation Catalyst

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